Heat exchange apparatus



June 25, 1940.

HEAT EXCHANGE APPARATUS FiledAug. 3, 1937 4 Sheets-Sheet 1 K0 5 Q INVENTOR H q I Oscar [1. Olson, Jr. B

ATTORNEY o. A. OLSON, JR Q 2,205,431

o. A. OLSON, JR 2,205,431

Filed Aug. :5, 19s? 4 Sheets-She et 2 HEAT EXCHANGE APPARATUS V INVENTOR Oscar A. Olson, Jr.

June 25, 1940;

1 1/ I I/ 1/ 1; 1/ x I, 1/ 1/ 1 /1/ 1/ 1/ June 25, 1940.

O. A. OLSON, JR

HEAT EXCHANGE APPARATUS Filed Aug. 3. 1937 4 Sheets-Sheet 3 INVENTOR Oscar A. Olson, J

W x/EL RNEY June 1940. o. A. OLSON, JR 2,205,431

HEAT zxcamsz APPARATUS Filed Aug. 3, 1937 4 Sheets-Sheet 4 8 Tic 7.

INVENTOR t .1 in

Patented June 25, 1949 UNITE STATES ATENT OFFICE HEAT EXCHANGE APPARATUS- Oscar A. Olson, Jr., Scarsdale', N. Y. Application August 3, 1937, Serial No. 157,089

15 Claims. (or. 25749) I This invention relates to heat exchange apparatus and more particularly to an apparatus for heating or cooling and agitating liquids, and the like.

One of the objects of this invention is to provide a simple, practical and efiicientapparatus for heating, or abstracting heat from, substances particularly liquid or semi-liquid, hereinafter for convenience termed liquid. Another object is to provide a simple, practical and emcient apparatus for agitating liquids, such as liquids under temperature change or control. Another object is to provide apparatus of the above-mentioned character which will be of strong, dependable and compact construction, and. capable of efficient and inexpensive manufacture. Another object is to provide apparatus of the above-mentioned character adapted particularly for operation upon liquid, semi-liquid and like food products, such as milk, cream, and the like, constructed so as to achieve dependable and efficient sanitation and to permit of speed, ease and inexpensiveness of maintenance of cleanliness or sanitation.

Another object is to provide apparatus of the above-mentioned nature in which the fluid,

vapor, liquid, or like medium that is used to withdraw heat from or impart heat to the product being treated may be dependably, efiiciently and conveniently handled; exposed to the product being treated for heat interchange at high efiiciency; and, particularly where food or like products are treated, handledwith minimum risk of commingling with or contaminating the product undergoing treatment.

Another object is to provide an efficient apparatus for agitating materials, such as liquids, for example, of the kind above-mentioned, and that will be compact, of high capacity per unit volume, and characterized by structural features and mode of operation that will dependably achieve minimum wear on moving parts. Another object is to provide an apparatus of the above-mentioned character capable of efficient action at comparatively low speeds, thus 3.130130 achieve the advantages attendant upon -low speed-of rotation of moving parts.

Another object is to provide an apparatus of the above-mentioned character in which sheet metal may be employed without detracting from durability, strength, and ruggedness of construction. Another object is in general to improve the structural and functional characteristics of heat exchange and agitating apparatus, as here-, tofore known, to achieve higher capacity, greater efficiency, and also advantagesin manufacture, operation, and maintenance. Another object is to provide an apparatus of the above-mentioned character that will be well adapted to meet the widely varying conditions of hard practical use. Other'objects will be in part obvious or in. part pointed out hereinafter. v

The invention accordingly consists in the features of construction, combinations of elements,- and arrangements of parts as Willbe exemplified in the structure to be hereinafter described and the scope. of the application of which will be indicated in the following claims. In the accompanying drawingsin which are shown several of thevarious possible embodi ments of my invention, I

Figure lis a central vertical longitudinal sectional viewthrough one-form of apparatus;

Figure 2 is a transverse sectional view thereof, as seen along the line 22 of Figure 1; v Figure 21% is a perspective view on a smaller scale showing a possible external configuration which the rotor or rotors of the various forms or embodiments of my invention may be given or assume; .1

Figure -3 is a central verticallongitudinal sectional view of another form of apparatus;

Figure 4 is a transverse-sectional view, as seen along the line 4-4 of Figure 3; I

I Figure 5 is a central vertical longitudinal sectional view of another form of apparatus;

Figure 6 is a transverse sectional view, as seen along the line 6-45 of Figure 5; Figure '7 is a central vertical longitudinal sectional view of another form of apparatus, cers tain parts, however, being diagrammatically indicated;

Figure 8 is a transverse sectional view, as seen along the line 88 of Figure7, being, however, partially diagrammatic.

Similar reference characters refer to similar parts throughout the several views in the drawings.

As conducive to a clearer understanding of certain features of my invention, it might at this 5 point be noted that there exists frequent occasion for theheat-treatment, under agitation, of

that, While the apparatusof my invention has particular advantages in connection with treatment of such products and in the following description will be described in connection with milk, that is not to be interpreted by way of limitation and hence the term milk or liquid product as employed hereinafter, is to be understood and interpreted in a broad and not a limiting sense.

Referring now to Figures 1 and 2, I provide a container or vat generally indicated by the reference character l0 and preferably give it a shape as shown in the drawings in that it has upper side walls II and 12 which may be substantially parallel and which merge downwardly and inwardly to meet and form what will here inafter be termed the bottom l3 which is preferably given an appropriate radius of curvature and illustratively a curvature of substantially 180, the vat Ill being closedmby endwalls l4 and I5 of appropriate shape. If desired and preferably the vat I0 is made of a suitably heavy sheet metal and may be supported in any suitable manner as by standards lG-IB.

The vat I0 is to receive the milk or liquid product to be treated and any suitable means (not shown) may be provided to supply the vat with the liquid or fill it to an. appropriate height and to remove or withdraw the liquid therefrom.

Preferably, also, a suitable closure is provided at the top of the vat and, illustratively, that may comprise a central sheet-like member I! bridged across from end wall l4 to end wall I5 and secured thereto in any suitable manner and having hinged thereto, as at 18 and IS, the cover or closure members 20 and 2|, respectively. These parts also may be made of sheet metal and preferably are constructed to give an opening or access to the interior of the vat and the parts contained therein, later described, for various purposes, such as cleaning, and the like.

The vat, including the various walls thereof, as described above, and also the top closure or closures therefor, are preferably constructed in any suitable manner to be resistant to the conductivity of heat and for this purpose any appropriate heat insulating means may be employed for lining the sheet metal shell of these parts,

there being provided, if desired, an external sheet metal shell for mechanically protecting and covering over the heat insulating material.

In the end walls l4 and I5 and'preferably alined along thelaxis of curvature of the bottom [3, are holes 2223, preferably rounded, and related thereto are suitable means forming bearings for the end shaft-like members 2425 of'a rotor that is within the vat ill and is generally indicated in Figures 1 and 2 by the reference character 26. Illustratively, end wall l4 may be provided with a suitable bracket 21 which supports a bearing member 28 in which'the sleevelike shaft or trunnion member 24 is rotatably supported, a suitable liquid seal, such as a stufling box, indicated at 29, coacting with the apertured end Wall [4 and the member 24 to prevent leakage of the liquid from the vat llU through the hole 22 and along the shaft 24.

In like manner, end wall l5 may have related to it a bracket 30 which supports a bearing member 3| in which the shaft member 25 is rotatably supported, a stuffing box or seal 32 functioning like the member'29 at the end wall I4. The rotor 26 is driven by any suitable means, preferably through one of its sleeve-like shaft members; Thus, for example, a driving member in the form illustratively of a pulley 33 may be secured to the shaft member 25 adjacent the bearing 31 and may and preferably, any suitable speed change means limitation, I have shown it in the form of a fivepointed star presenting, therefore, five members A, B, C, D and E, individually substantially triangular in cross-section and extending substantially from one end wall l4 to the other end wall 15.

A preferred mechanical construction for the rotor 26 of Figures 1 and 2 comprises two heads 36 and 31 preferably cast and also preferably cast integrally with the sleeve-like shaft members or trunnions 24, 25, respectively; the heads 36,31 are preferably identical and hence it will suffice to describe only one of them in detail.

Thus, head 36 (Figures 1 and 2) comprises a star-shaped end wall 38 stepped as shown in Figthis stepping, as better shown in Figure 1, being preferably provided so as to space the triangular radial extensions of the end wall 38, correspondright-hand edge is rabbeted, as at 40 throughout its star shape.

The head 36 is closed off along the plane of the right-hand edge of the axial star-shaped wall 35 by a wall 4|, also star-shaped, and in the latter and facing toward the right, as viewed in Figure 1, are formed parallel spaced flanges or ribs 42, 43 which in outline (see Figure. 2) have a star shape similar to but smaller than the star shape that outlines the peripheral wall 39 of the head 36, forming therebetween a star-shaped groove .44.

The wall 4| is broken through or apertured as at 45 (see Figure 2) but, in this embodiment, preferably only throughout the area between the star-shaped rabbet or flange 40 and therib 42.

In like manner the head 31 is provided with a rabbet 46 and a groove 41 corresponding, respectively, to the rabbet 40 and groove 44 of the head 36 and respectively facing toward each other.

With its respective star-shaped end edges received in the star-shaped grooves 44 and 4! of the heads 36 and 31, respectively, is an internal star-shaped sheet metal member 50. Internal member 50 may be made up of a single sheet of sheet metal and hence with a single longitudinally or axially extending seam which is sealed as by welding, brazing, soldering, or the like, and which may extend along the apex of one of the triangular or point portions of its cross-section, or it may extend elsewhere as, for example, at the junction of two sides of two of these parts. Or it may be made up in any other appropriate or suitable manner such, for example, as making it up in'several V-shaped axially extending sections with a correspondingly appropriate number of axially extending joints or seams. With its ends fitted into the grooves 44 and 41, as above noted, the resultant two end junctions are sealed and mechanically joined as by welding, brazing, or the I ure 1 to merge into the hollow shaft member 24,

like, this joining being carried on, of course, while maintaining in any suitable manner proper coaxial relationship of the trunnions 24 and 25. The two heads are thus rigidly joined together, the internal star-shaped member 50, in this embodiment, enclosing a hollow sealed axially extending space.

Thereupon and preferably there are secured, in appropriate or suitable number, illustratively one for each axially extending face or side of a triangular or point part of the member 50, longitudinally extending and preferably imperforate bracing and channel-subdividing members 5| which conveniently are of appropriately heavy sheet metal and given the cross-section, for example, of structural channel. They may be welded or otherwise secured along the outer faces of the member 50 and extend from one head 36 to the other head 3?.

Into the star-shaped groove or rabbet 46 is then fitted an external star-shaped sheet metal member 52; this may be constructed in any suitable manner, as indicated in connection with the sheet metal construction of the internal member 50, and its junction to the heads 36 and 31 at the respective rabbets, is sealed and made mechanically secure as by welding, brazing, or the like.

Between the sheet metal star-shaped shells or members 56 and 52 there is thus formed a continuous axially extending space or passage which in cross-section has a shape which is the outline of substantially a star and which at its respective ends is in communication with the interior of the heads 36 and 31 by way of the apertures 45 in the end walls M of the two heads,

these apertures being, as above noted, confined to the star-shaped space outlined between the junctions of the internal and external star-shaped,

sheet metal members 50 and 52 with the heads. The hollow interiors of the heads 36 and 31 are, as indicated in Figure 1, in communication with the interiors of the sleeve-like trunnions 24 and 25 and by any suitable means, as the rotor 26 is rotated at a suitable speed, a suitable medium fluid, such as a vapor or liquid, is passed through the resultant continuous passageway from one trunnion to the other. For example, a suitable pipe 55 may be connected to a pipe fixture or coupling 56 secured as at 51 to the end bracket 21 and in sealed connection with the rotating open ended trunnion 2 as by a suitable stuffing box construction 58. Where a liquid is to be used, such as water of appropriate temperature for heat-treating milk, pipe 55 may be in communication with any suitable source of such liquid, such as a water heater diagrammatically indicated at 59, through a circulating pump diagrammatically indicated at 69," whence the passage of the liquid through the trunnion 24 into the head 36 and through the above-mentioned passageway between the two star-shaped shells or members 50 and 52 and thence into the head 31 to be discharged through the hollow shaft member 25, is assured; the shaft member 25 preferably has related to it a suitable pipe coupling 62, carried by the bracket3ll, and in sealed 'con-. nection with the rotating shaft 25 through the stuffing box construction 63, and the pipe coupling member 62 has connected to it a pipe '64 through which the discharged medium may be returned for reconditioning to the apparatus 59.

The longitudinally extending members 5| (Figure 2) are preferably provided to break upthe passageway between the star-shaped members 56 and 52 into a plurality of individual channels to minimize interference with the desired action by the rotary movement of the rotor. Thus, the operating medium such as the hot water is dependably caused to flow in an axial direction from one head to the other, in a plurality of individual and separately guided streams or com- I ponents and this arrangement is preferred, particularly where the medium employed is liquid,

and may be affected by the rotational movement I of the rotor in such a way as to cause flow in a direction or directions departing from axial direction. Also, the members contribute toward providing greater resistance to or strength against any tendency of the product being operated upon in the vat to bend or warp the sheet metal inwardly of its plane. 1 v

Preferably, also, the apexes of the angles formed by the longitudinally extending adjacent portions of the sheet metal of the internal and external members are rounded over, it being preferred to avoid sharp internal or external corners, particularly with respect to the external sheet metal member 52. With such rounding'off at the corners, the bending of the sheet metal into its shape is facilitated and weakening, as happens with certain metals, at the bends is avoided.

' such relative proportions that, particularly where milk or milk products are operated upon, the rotor 26 remains submerged during its operation, and preferably the rotor is positioned at the axis ofcurvature of the bottom I3 where the vat is given, as is preferred, a curved bottom.

During operation, and bearing in mind the above-described passage or circulation through the rotor 26 of the heat-transferring or heat-abstracting medium, the rotor 26 is rotated at'an appropriate speed; by way of illustration, where milk is operated upon, the rate of rotation may be as low as 15 or 18 R. P. M., and this low speed with its many attendant advantages, I am enambled to arrive at by reason of the peculiar and highly efficient agitation of the milk, which the rotating rotor 26 achieves. Viewing Figure 2, the rotor 26 effects a continual transfer of the product undergoing treatment from one side of theaxis to the other; below the horizontal plane of the axis, assuming the rotor to be moving in clockwise direction, the parts, such as part B, effects a movement of the product toward the left and upwardly and above the above-mentioned horizontal plane the rotor effects a definite and positive transfer of the product from the left of the axis to the right, two adjacent parts, such as parts D and E of Figure 2, acting like a trough virtually to lift or carry the liquid over the axis from the left to the right. At the same time and particularly where, as earlier above noted, the end Walls of the heads 36 and 3! are stepped so as to space the outer portions thereof from the end walls 14 and 15 of the vat, there may take place, particularly where the rotor is not completely submerged in the product, a discharge out of such a trough at both ends thereof in-an axial direction. This action of effecting a discharge at one or both ends of the rotor may be facilitated and increased, if desired, by maintaining the so-called star-shaped cross-section and preferably with its other features of construction but giving the parts A, B, C, etc., alielical form withxrespect to the axis of rotation of the rotor or by providing on the exposed surfaces of the rotor appropriate blades or vanes at appropriate angles orcurvatures; Figure 2 illustrates one such form. I

. -It will thus be seen that all parts of the prodnets in the vat undergoing treatment are repeatedly brought into contact with the exposed surfaces of the rotor 26 and thus a rapid and dependable exchange of heat betweenthe product and the medium passed through the rotor is brought about. Also, where the product is of a charactersuch'as certain milk products where churning has to be avoided, I am enabled to effect rapid heat interchange and to utilize such a low speed of rotation that danger of churning is dependably eliminated. Where lower speeds are thus made possible, I am enabled to simplify the sealed connections between the vat and the rotating shaft or trunnion parts, maintain the seals such'as by the use of ordinary stufling boxes dependably, and also greatly, if not entirely, eliminate problems of lubrication of the shaft members in their bearings and the problem of preventing oil or like lubricant from working its way into the vat.

Under certain circumstances it may be desirable to achieve the. advantages of having the intake and outlet for the operating medium, such as the heat-conveying or heat-abstracting medium positioned at one end of the apparatus and toachieve other advantages; in such case I may embody the apparatus in the form shown by way of illustration in Figures 3 and 4 in which the two heads 66 and 61 are again star-shaped and on their walls or faces that face toward each other have the rabbets 40 and 46 for receiving the outer sheet metal member 52 and, instead of the grooves 44 and Al, as in Figure l, are provided with rabbets 68 and 69 for receiving and having secured thereto the inner star-shaped sheet-metal member 50. The adjacent transverse end walls of the heads 66 and 61 are again apertured as at 45 so that the interiors of the heads are in communication with the space or passageway between the two sheet metal members 50 and 52. However, this wall in the head 67 is also apertured as at 10 (Figures 3 and 4) so that-the interior of head 61 is now in communication with the interior of the inner star-shaped shell 50. Likewise, the end wall of the head 61 isapertured as at H, but the head 66 has an internal wall 12 that is in communication with a sleeve or tube-like. member 13 that extends coaxially with the hollow shaft member M of the head 66 and is longer than the latter so as to extend beyond it. The sleeve member '13 extends through a pipe coupling member 15 which, as at 76, may be coupled to the intake pipe 55 in a suitable system or circuit as was described above in connection with Figure 1; the coupling member 76 is carried or secured'to the bracket ,2! which carries the bearing 28 in which the sleeve shaft 14 is rotatably supported. As in Figure 1, the coupling member 16 is in sealed connection with the shaft M by way of a stuffing box or. like seal '11, comparable to the stuffing box 51 of Figure 1.

The inside hollow shaft 13 being of smaller diameter than the hollow shaft 14, leaves an adequate passageway through the latter and extends to the left through the coupling member 16 by way of a stufiing box or like seal 18 through which its internal passageway is connected to a pipe coupling member 19 to which the return or exit pipe 64 of the above-mentioned system or circuit may be connected as suggested in Figure 1.

Accordingly, the operating medium enters the rotor of Figures 3 and 4, generally indicated by the reference character 80, by way of the pipe 55, sleeve shaft 14, the head 66, the passageway between the interior and exterior shells 50 and 52, thence through apertures 45 to the interior of head 61, whence it enters the interior of the interior shell 50 through the aperture 10 in the head 61, and passes out of the interior of shell 50 by Way of apertures H and the connecting passage or passageway in the head 66 that connect the apertures H to the hollow shaft 13, whence it is discharged through the pipe 64-.

In numerous respects the actions that may be made to take place are like those described above in connection with Figure 1, it being noted that here again I prefer to employ the channel subdividing and strengthening ribs or structural members 5! (see Figure 4) to effect better movement and. distribution and guiding of the operating medium through the rotor.

With the arrangement of Figure 3, I may achieve a better temperature gradient from one end of the rotor to the other in that the return flow of the operating medium through the interior of the inner shell 50 coacts through the walls of the latter with the incoming operating medium within the outer shell 52 to effect heat interchange and in coaction with the product in the vat that is undergoing treatment bring about substantially the same temperature throughout the axial length of the rotor 80.

If desired, I may achieve different rates of flow of the medium in the two passageways, namely the outer passageway between the two shells 50 and 52 and the passageway or passageways within the inner shell 50, by appropriately proportioning the relative cross-sectional areas thereof. Illustratively, I may find it desirable under certain circumstances to have a faster rate of flow through the inner passageways which I may conveniently restrict as by interposing between the two heads 66, 6'! and within the inner shell 52 suitablemeans for cutting down the efiective cross-sectional area of the shell 50. Illustrative- 1y, I may extend through the inner shell 56 an inner tubular member 8|, preferably of sheet metal, or the like, arranged coaxially with the rotor and seated in annular grooves 82, 83 in the heads 66, 61, the junction being sealed and secured as by welding, brazing, or the like. The interior of the innermost shell 8| is thus sealed and depending upon its cross-sectional area it correspondingly reduces the cross-sectional area of the path of flow through the inner shell 50. Illustratively, and as shown in Figure 4, the inher member 8| may be so proportioned that it sub-divides the interior passage otherwise provided by the interior shell 50 into as many individual passages or channels as the shell 50 has points or arms, or flutes, illustratively five, as is indicated in Figure 4. Thereby the total cross-sectional area of the return path for the operating or treating fluid is materially lessened and illustratively is made less than the crosssectional area of the path or paths provided between the inner and outer shells 50 and 52; as a consequence the velocity of flow in the return paths is greater than the velocity of flow in the others. And accordingly, by appropriately proportioning these cross-sectional areas in appropriate relation to the pressure or velocity of flow of the treating fluid, as by way of the pump 60,

for example, any suitable or desired relationship of interaction between the fluid in the two paths may be achieved.

As illustrative of other possible forms which the rotor may take, I may also cause a central tubular member, like the member at of Figures 3 and 4, to function as a path for the return flow of the treating fluid either in the relationship to an outer path or paths of flow, as in Figure 4, or by way of an arrangement like that shown in Figures 5 and 6 where the rotor, generally indicated by the reference character 85, is again and preferably star-shaped in cross-section and comprises an outer sheet metal star-shaped member 52 and an inner tubular member 88, appropriately related to heads 8'! and 88, as by way of the rabbets 40 and 48 in. the two heads for receiving the outer shell 52 and annular grooves 89 and 90 for receiving the respective ends of the inner tubular shell 86, the junctions being secured and sealed, as by welding, or the like. These rabbets and grooves are preferably so formed and related that when the inner and outer shells are related thereto, the outer shell 52 is substantially tangential to the inner cylindrical shell 88 along apexes of the angles formed between adjacent points or arms and thereby the outer passageway for the treating fluid comprises as many individual passageways as there are arms or points in the cross-section of the shell 52 while the return passageway is formed by the interior shell 88.

The head 81, like the head of Figure 3, is constructed to provide an outer sleeve-like shaft member 14 which is connected with the interior of the head 81, as shown, and with the individual passageways in the outer shell 52 by way of appropriate apertures 9! formed in the star-shaped end wall of the head B'l; these passageways communicate with the interior of the head 88 at the other end through similar apertures 92 in the star-shaped inner end wall of the head 88, the interior of the head 88 communicating with the passageway formed by the interior shell 88 by way of an opening or aperture 93 positioned I coaxially and in coincidence with the open end of the coaxial inner shell 88. Through the inner shell 88 the treating fluid may pass in a direction toward the left, as viewed in Figure 5, taking part in a heat-transferring or heat interchange action with the treating fluid passing through the outside passageways or channels, whence it passes through an opening 94 in the end wall of the head 8'! and thus placed in: communication with the inside hollow shaft member 13. The hollow shaft members 13 and (4 may be connected to a circulating path or system, like that shown in Figure 3, and by connections like those of Figure 3 and described in detail in connection therewith. In action and operation the form of apparatus of Figures 5 and 6 will now be clear and understandable in view of what has already above been set forth in detail.

Where the rotor has also an interior shell. like the shell 59 of Figures 2 and 4, or shell 88 of Figure 6, the interior shell also and materially strengthens the rotor construction though it will be understood that the illustrative configuration above described as given to the outer shell 52 is one which, though I may, and preferably do, employ sheet metal, of itself has great strength and rigidity, the various angles between succeeding faces resulting in a structure offering very substantial resistance to distortion, warping,

stand the strains of driving on the one hand and the resistance ofier'ed by the material in the vat undergoing treatment.

In Figures 7 and 8 is shown an apparatus comprising a vat 96 constructed in general like the vat [9 of the preceding figures excepting that, as viewed in section as in Figure 8, it is of greater width in order to accommodate therein several rotors, illustratively two rotors generally indicated by the reference characters R and R These rotors are preferably'substantially starshaped in cross-section, illustratively having five arms or points, and they may take forms as to specific features of construction like those described above in connection with Figures 2, 4 and 6, each having shaft extensions or trunnions, as indicated in Figure 7, preferably related to and mounted in the end walls .by bearing means and sealing means, such as was earlier above described in connection with Figures 2 and 3. Likewise their interior channel or channels may be connected by pipes, and the like, to a supply or circulating system for the treating fluid, and that system may be arranged in the manner shown in Figure 1 or in the manner shown in Figure 3. Thus, treating fluid may be supplied each rotor as it is rotated.

However, the plurality of rotors in the vat 96 (Figure 8) have preferably the same number of arms or points, illustratively five, and the two rotors are geared together as by gears 91 and 98 (Figure '7) fixed on the shaft extensions of the rotors, such as the extensions 99 and I09; gears 91 and 98 are preferably of the same size and number of teeth so that, where the rotors (Figure 8) have the same number of projecting arms or points, the relationship of the latter as the two rotors rotate is maintained invariable, it being understood that, as shown in Figure 8, the rotors occupy such a relative angular position that the arms thereof mesh together, somewhat like the teeth of gears, but without at any time contacting each other. Thus, in Figure 8, it will be seen that one arm or point I 0| of rotor R bisects the angle between the adjacent faces of two succeeding arms or points I02, I03 of the adjacent rotor R the spacing of the rotors being such that as they rotate their respective arms or points preferably do not come in contact with each other and preferably leave always a space or channel therebetween.

The material to be treated is placed in the vat 96 to an appropriate depth which, as above indicated, is preferably sufiicient to submerge the rotors where the product undergoing treatment is a milk product, the treating fluid is supplied to the rotors in a manner that will now be clear, and heat transfer takes place accompanied by a highly efficient agitation. Thus, assuming that the rotors are driven in the respective directions indicated by the arrows in Figure 8, and at ap propriate speed, the projecting portions of the rotor R below its axis effects a movement of the liquid undergoing treatmentin a direction toward the left and as rotation continues in a direction upwardly along the left-hand wall of the vat, as viewed in Figure 8. A similar action takes place with respect to the parts of rotor R excepting that the liquid is moved toward the right in the vat 8 and upwardly along the right-hand wall thereof, as viewed in Figure 8. Thereafter, the liquid is moved or carried over the respective axes of the rotors and in the arrangement of Figure 8 the two streams or portions are carried or moved from the respective side walls of the vat toward the central plane thereof, whence the conjoint downward action of the projecting parts of both rotors in this region is effective to move the liquid downwardly between both rotors as the rotation thereof continues. At the same time, actions like those described above in connection with, for example, Figure 2, take place with respect to agitating the liquid in the vat, moving it axially, and otherwise intimately contacting it with the large surfaces of the rotors, but with an arrangement like that of Figure 8 a steady circulation of the liquid also takes place, in a plurality of circuits, one for each rotor, each circuit being generally circular with its center substantially at the axis of the rotor; but the plurality of circuits, illustratively two in the arrangement of Figure 8, have a certain channel, that is, between the two rotors, common thereto, and hence the liquid in the two circulating paths or circuits becomes commingled. Accordingly, the liquid is repeatedly subdivided and commingled and a thorough and highly eflicient agitation-thereof takes place. These actions thus insure that all portions of the liquid undergoing treatment are brought into contact repeatedly with the outer surfaces of the rotor or rotors through which surfaces the heat interchange takes place.

By such actions as these, eflicient and rapid heat exchange ensues and the time of treatment may be reduced. It will be understood, of course, that the heat flow may be in either direction, that is, from the treating fluid in the interior of the rotor or rotors to the material in the vat being treated, or vice versa; a typical illustration of the former is in the heat treatment of milk, and the like, as for example, where milk is raised to a temperature on the order of 145 F. The treating fluid may, however, be of lower temperature than the liquid or material being treated in the vat in which case the latter is cooled; if desired, therefore, the treating fluid in the rotor or rotors may take the form of any suitable or appropriate refrigerant. For example, it may take the form of brine in which case the conditioning apparatus59 (Figures 1 and 3) may be any suitable means or apparatus for cooling or refrigerating the brine. And, in so far as certain features of my invention are concerned, particularly with respect to such features embodied in the various illustrative forms of my invention (whether or not they include the helical rotor feature of Figure 2 as achieve agitation and movement of the material undergoing treatment, any suitable or appropriate means for effecting, achieving or maintaining a suitable temperature differential between the rotor or rotors and the material undergoing treatment may be employed to effect heat-interchange where the latter is desired.

Thus, it will be seen thatmy invention achieves numerous advantages, some of which have been pointed out above. Also, it might be noted that the rotor construction may beembodied in form which has'a displacement comparable to or even less than the displacement of the active parts of heretofore known apparatus, all while maintaining a large surface exposed to the material undergoing treatment. The repeatedly reentrant external surface of the rotor or rotors makes it possible to achieve a wide range of ratio of exposed surface area to displacement, depending upon the number of arms or points, their radial dimension, and configuration, and thus I am enabled to meet a wide variation of practical requirements. I have above pointed out, also, that I am enabled to operate at relatively low speeds of rotation of the rotor or rotors; this has the advantage that more viscous fluids may be efficiently and quickly treated. For example, I may employ a lower speed for treatment of soups of thick consistency than for ordinary milk, and still achieve rapid heat-interchange and effective agitation. Where food products are treated according to heretofore known apparatus, one of the serious disadvantages and difficulties is the lack of ease in effecting cleaning of the apparatus, particularly of the rotor; however, by my construction this disadvantage is effectively overcome in that the rotor may be constructed to present a plurality of exposed plane surfaces or faces, as illustrated above, which are easily cleansed and easily made accessible for cleansing through the top closure or closures, by simply bringing the arms or points of the rotor or rotors successively into appropriate upwardly exposed position. Furthermore, it will be seen that the apparatus is of a thoroughly practical nature and well adapted to meet the varying conditions of hard practical use.

As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth, or shown in the accompanying drawings, is-to be interpreted as illustrative and not in a limiting sense.

I claim:

1. In apparatus of the character described, in combination, a container having mounted therein a plurality of rotors with means rotatably supporting said rotors for rotation about respective axes spaced from each other, said rotors being hollow and having connections for passing through them a fluid medium between which and the contents of said container heat exchange is to takeplace, said rotors having external configurations that provide in the surface of each a plurality of axially extending and radially projecting portions that alternate with reentrant portions to provide spaces between adjacent projecting portions, and means for driving said rotors in respective directions and in such synchronism that the projecting portions of one rotor, in passing an adjacent rotor, move successively in juxtaposition to successively presented reentrant por tions of the adjacent rotor.

2. I11 apparatus of the character described-in combination, a container having mounted therein a plurality of rotors with means rotatably supporting said rotors for rotation about respective axes spaced from each other, said rotors being hollow and having connections for passing through them a fluid medium between which and the contents of said container heat exchange is to take place, said rotors having external configurations that provide in the surface of each a plurality of axially extending and radially projecting portions that alternate with reentrant portions to provide spaces between adjacent projecting portions, said rotors each having the same number of projecting portions, and means for driving adjacent rotors in opposite directions about their respective axes and at the same speed whereby the projecting portions of one rotor move successively into the successively presented intervening spaces of the adjacent rotor.

3. In apparatus of the character described, in combination, a container having mounted therein a plurality of rotors with means rotatably supporting said rotors for rotation about respective axes spaced from each other, said rotors being hollow and having connections for passing through them a fluid medium between which and the contents of said container heat exchange is to take place, said rotors having external configurations that provide in the surface of each a plurality of axially extending and radially projecting portions that alternate with reentrant portions to provide spaces between adjacent projecting portions, and means for driving adjacent rotors in opposite directions about their respective axes thereby to cause adjacent projecting portions of adjacent rotors to move in the same direction through the plane joining the axes of rotation of said adjacent rotors, thereby to cause driving said rotors to efiect agitation and movement of the contents of said container, the reentrant or trough-like portions of said starshaped rotors acting, as said rotors rotate, to lift and carry a portion of said contents over the axis of rotation and hence to move it from one portion of the container to another.

5. In apparatus of the character described, in combination, a container having therein a plurality of rotors and means rotatably supporting them. each of said rotors having an external configuration the outline of whose cross-section approximates that of a star, at least one .of said rotors having passage-forming means therein for guiding a fluid therethough for heat interchange with the contents of said container, and means for driving said rotors to effect agitation and movement of the contents of said container.

6. In apparatus of the character described, in

combination, a container having therein two adjacent rotors and means rotatably supporting them for rotation within said container, said rotors each having an external configuration to provide a plurality of axially extending pro t ing portions with intervening reentrant portions that provide an axially extending space between adjacent projecting portions, at least one of said rotors being hollow to. receive a fluid between which and the contents of said container heat exchange is to take place, said external configuration of the hollow rotor providing a large surface area through which heat exchange between said fluid and the contents of the container contacting said surface can take place, and means for driving said rotors in respective directions and at respective speeds to cause the projecting portions of one rotor to move successively into the successively presented spaces of the adjacent rotor, thereby to effect agitation of the' contents of said container-andto bring all portions of said contents successively andultimately into contact with the surface through which heat exchange takes place.

7. In apparatus of the character described, in combination, a container having therein two' adjacent rotors. and means rotatably supporting them for rotation within said container, said rotors each having an external configuration to provide a plurality of axially extending projecting portions with intervening reentrant portions that provide a space between adjacent projecting portions, at least one of said rotors being hollow to receive a fluid between which and the contents of said container heat exchange is to take place, and means for driving said two rotors in opposite directions about their respective axes and at respective speeds such that a projecting portion of one rotor, in passing the other rotor, is juxtaposed to a moving reentrant portion of said other rotor.

8. The combination with a container for receiving a liquid product for heat exchange with a fluid medium, said container having opposed end walls, of rotor means comprising two end heads having shaft means, said opposed end walls having-bearing means for rotatably supporting said shaft means, and two members each of sheetlike material and of sleeve-like form but one within the other so as to provide a space therebetween extending from head to head and in sealed connection therewith, the outermost of said members having a configuration to provide a plurality of axially extending and radially projecting .portions with trough-like portions intervening adjacent projecting portions, and connection means for supplying through at least one of said shaft means and to the space between said two members a fluid medium between which and said liquid product in the container heat exchange is to take place as said rotor means rotates.

9. An apparatus as claimed in claim'8 in which the inner of said two members has a configuration substantially similar to that of the outer of said two members.

10. An apparatus as claimed in claim 8 in which the inner of said two members is substantially circular in cross-section.

11. An apparatus as claimed in claim 8 in which the inner of said two members has a configuration substantially similar to that of the outer of said two members, there being a third member extending from head to head but within the inner of said members.

12. An apparatus as claimed in claim 8 in which there is a metallic member that is hollow and. extending within the inner of said two members and from one head to the other.

13. An apparatus as claimed in claim 8 in which the inner of said two members is substantially circular in cross-section and in which the apexes of said trough-like portions are substantially tangential thereto. I

14. An apparatus as claimed in claim 8 in which said heads are each provided with means forming two seats, each for receiving therein an .end of one of said members and having a conrotatably supporting said shaft extension, means for driving said rotor means; and connection means operatively connected to said hollow shaft extension to provide said passage with a fluid medium between which and the liquid product in said container heat exchange isto take place.

OSCAR A. OLSON, JR. 

